Developing an Ostreopsis Early Warning System: the joint engagement of scientists, environmental agencies, and community science

In the last twenty years blooms of the harmful benthic dinoflagellate Ostreopsis, affecting human and environmental health, have become a common seasonal phenomenon in many temperate areas. Therefore, implementing an Early Warning System (EWS) of benthic harmful algal blooms (BHABs) is needed. While most routine monitoring programs are focused on plankton, collecting benthic samples is important in order to evaluate the stock of toxic microalgae. In the Mediterranean, several administrations have been conducting BHABs monitoring using scientific approaches in coordination with research centres. For an EWS to be effective, samples should be collected and processed soon and the results quickly communicated to the users. In the frame of the CoCliME project, an easy and reliable BHAB-sampling protocol was co-designed and implemented by scientists and stakeholders. Scientists produced and provided sampling kits and training sessions. Results (Ostreopsis abundance and risk level) were shared on coordinated online platforms between scientists and public agencies. This protocol has been successfully tested in Catalonia and France during the summers 2020 and 2021. It was proven to be an effective EWS for authorities to quickly raise recommendations on the health risks associated with Ostreopsis blooms in Mediterranean beaches. The protocol also contributes to build time series for elucidating climate change effects on Ostreopsis blooms.Corresponding author's email: magda@icm.csic.e